JPH0735802B2 - Speed control circuit with variable displacement hydraulic pump - Google Patents

Description

The present invention relates to a speed control circuit having a variable displacement hydraulic pump suitable for use in a hydraulic crane or the like.

B. Conventional Technology FIG. 3 shows a conventional example of the speed control circuit disclosed in Japanese Patent Publication No. 59-5163.

The operation pilot valve 1 converts the pressure oil supplied from the hydraulic pump 2 into a pilot pressure proportional to the operation amount of the lever 1a and outputs the pilot pressure to the pipeline 3a or 3b. The pilot pressure in the pipelines 3a and 3b is the pilot ports 4a and 4b of the pilot type control valve 4.
, And the control valve 4 is switched and driven according to the pilot pressure. Further, the pilot pressure in either one of the pipelines 3a, 3b is taken out from the shuttle valve 11, and the pipeline 16,
It is guided to the regulator 7a of the variable displacement hydraulic pump 7 through the electromagnetic switching valve 6, and the hydraulic pump 7 is driven by the regulator 7a.
Is controlled variably in proportion to the pilot pressure.
The oil discharged from the variable displacement hydraulic pump 7 passes through the control valve 4 to drive the hydraulic motor 8.

The electromagnetic switching valve 6 is switched between the a position and the b position by turning the switch 9 on and off. When the switch 9 is off and the switching valve 6 is in the a position, the output pressure of the pilot valve 1 is supplied to the regulator 7a through the switching valve 6, and the discharge capacity of the variable displacement hydraulic pump 1 is increased or decreased according to the pilot pressure. The speed of the hydraulic motor 8 is variably controlled according to the opening area of the control valve 4 and the discharge capacity. When the switching valve 6 is in the low position, the pressure from the pressure reducing valve 5 that generates a predetermined pressure is guided to the regulator 7a through the switching valve 6, so the variable displacement hydraulic pump 7
The discharge capacity of is fixed to a constant value. Therefore, the speed of the hydraulic motor 8 is variably controlled according to the opening area of the control valve 4 controlled by the pilot valve 1. If the pressure generated by the pressure reducing valve 5 is set to a small pressure, the discharge capacity of the variable displacement hydraulic pump 7 becomes a small value, so that the speed change of the hydraulic motor 8 with respect to the operation amount of the pilot valve 1 can be made small.
So-called fine speed control is possible.

In FIG. 3, 12 is a counter balance valve, 13 is a main relief valve, 14 is a pilot relief valve, and 15 is a battery.

C. Problem to be Solved by the Invention However, this Japanese Patent Publication No. 59-5163 only discloses a circuit consisting of one variable displacement hydraulic pump 7 and hydraulic pump 8, and is a normal hydraulic crane. Like 2
The circuit applied to the pump and the two-motor system is not disclosed.

The hydraulic crane includes a pair of hydraulic motors that can be independently driven as left and right traveling motors, respectively. For example, in FIG. 4, the hydraulic motor 8 is for right rotation,
The hydraulic motor 80 is for left rotation. Since it is necessary to control both hydraulic motors 8 and 80 at a constant speed when moving forward, as shown in FIG.
Guide to the electromagnetic switching valve 6 via 10, 11A, and the electromagnetic switching valve 6
The outlet pressure is branched and applied to the regulator 7a of the first variable displacement hydraulic pump 7 and the regulator 70a of the second variable displacement hydraulic pump 70 in common.

However, the circuit configuration as shown in FIG. 4 causes the following problems.

For example, in the underground wall bucket work using a hydraulic crane, one wire is wound around each of the main winding and the auxiliary winding winches to suspend the bucket. In order to raise and lower the bucket in a certain posture, it is necessary to drive the main winding and auxiliary winding winches at a constant speed. Therefore, when the circuit configuration of FIG. 4 is adopted, there is no problem if the efficiencies of the main and auxiliary winding hydraulic devices are exactly the same. However, if the efficiencies are different, the speeds of the hydraulic motors 8 and 80 are different even if the discharge volumes of the variable displacement variable displacement hydraulic pumps are the same, which causes a problem such as tilting of the bucket. A similar problem occurs in the horizontal retraction operation of the tower crane.

A technical problem of the present invention is that an equal capacity control mode and an independent capacity control mode can be selected among a plurality of actuators, and a variable speed control mode and a predetermined speed control mode can be selected for each actuator according to the work content. To do so.

D. Means for Solving the Problems The present invention will be described with reference to FIG.
The present invention includes a regulator 7 that variably controls the discharge capacity.
a and 70a having first and second variable displacement hydraulic pumps 7,70 for supplying pressure oil to the first and second actuators 8,80
And the first and second variable displacement hydraulic pumps 7, 70 for adjusting the flow of the discharge oil respectively.
First and second valve means for controlling drive of 8,80 respectively
4, 40, first and second valve control signals for individually controlling the first and second valve means 4, 40 and variable regulator control signals for individually variably controlling the regulators 7a, 70a, respectively. It is applied to a speed control circuit having two operating means 1 and 10.

And the above-mentioned technical subject is achieved by the following composition.

A first speed regulator control signal to be applied to the regulators 7a and 70a is output in addition to the variable regulator control signal for setting the discharge capacities of the first and second variable displacement hydraulic pumps 7 and 70 to a predetermined value. And the second signal output means 5 and 50 and the variable regulator control signal to the regulator 7
Speed mode switching means 6, 60 for switching between a variable speed control mode applied to a and 70a and a predetermined speed control mode for applying a predetermined speed regulator control signal to regulators 7a and 70a
And an independent capacity control mode in which a regulator control signal is independently applied to each regulator 7a, 70a, and an equal capacity control in which one of the regulator control signals is commonly applied to the first and second regulators 7a, 70a. And a capacity mode switching means 22 for switching between modes.

E. Operation When the independent capacity control mode is selected by the capacity mode switching means 22, the regulator control signal is independently applied to each regulator 7a, 70a. At this time, when the variable speed control mode is selected by the speed mode switching means 6 and 60,
The variable regulator control signal is applied to the regulators 7a and 70a. As a result, the discharge capacities of the hydraulic pumps 7 and 70 are independently controlled according to the operation amounts of the first and second operating means 1 and 10, and the actuators 8 and 80 are driven at different desired speeds. It

When the equal capacity control mode is selected, either one of the regulator control signals becomes the first and second regulators 7a, 7a.
Commonly applied to 0a. At this time, when the predetermined speed control mode is selected, one of the predetermined speed regulator control signals is applied to the regulators 7a and 70a, so that the discharge capacities become equal. The 8,80 are driven at a constant speed. When the variable speed control mode is selected, the discharge volume is made equal by the variable regulator control signal of either one of the operating means 1 and 10. Therefore, if the operating amounts of the operating means 1 and 10 are equal, the actuators 8 and 80 are equal. Driven at high speed.

It should be noted that, in the above-mentioned items D and E for explaining the configuration of the present invention, the drawings of the embodiments are used to make the present invention easy to understand, but the present invention is not limited to the embodiments.

F. Embodiment One embodiment of the present invention will be described with reference to FIG.
The same parts as those in FIGS. 3 and 4 are designated by the same reference numerals and will be described.

In FIG. 1, the first hydraulic motor 8 corresponds to the first control valve 4
Driven by the pressure oil supplied from the first variable capacity hydraulic pump 7 via the second hydraulic motor 80, and the second hydraulic motor 80 sends the pressure oil sent from the second variable capacity hydraulic pump 70 via the second control valve 40. Driven by. The control valves 4 and 40 are switch-controlled by the pilot pressures from the first and second pilot valves 1 and 10, respectively. The first and second variable displacement hydraulic pumps 7 and 70 are provided with regulators 7a and 70a, respectively, and their discharge capacities are controlled by the regulators 7a and 70a. Each regulator 7a, 70a has a solenoid valve 6, 6 60
When the pilot pressure from 1,10 is in the low position, the secondary pressure from the first and second pressure reducing valves 5,50 is applied alternatively. Further, the regulators 7a and 70a can communicate with each other through a pipe line 21 in which an electromagnetic switching valve 22 is interposed. When the electromagnetic switching valve 22 is demagnetized and is in the a position, both regulators 7a and 70a are cut off from each other, and when excited and are in the b position, both regulators 7a and 70a are communicated with each other via the conduit 21. . The electromagnetic switching valve 22 is switch-controlled by turning on / off the switch 23.

The check valve 24 between the switching valves 6 and 60 and the regulators 7a and 70a is configured so that the pressure in the pipeline 21 acts on the pilot ports of the control valves 4 and 40 when the switching valve 22 is switched to the b position. The check pressure is set to a pressure lower than the cracking pressure of the pilot valves 1 and 10.

In the speed control circuit thus configured, the following capacity control mode can be selected.

<1> Independent capacity control mode This is a mode in which the capacity of the hydraulic motors 8 and 80 is controlled independently, and is selected by switching the electromagnetic switching valve 22 to the a position.

In this case, the first and second regulators 7a and 70a are cut off from each other, and each regulator 7a and 70a is connected to each pilot valve.
Pilot pressure from 1,10 or 2 from each pressure reducing valve 5,50
The discharge volume is controlled according to the secondary pressure.

In this independent capacity control mode, the variable speed control mode is selected when the first and second electromagnetic switching valves 6 and 60 are switched to the a position, and the predetermined speed control mode is selected when switched to the b position. The variable speed control mode is a mode in which the displacement of the variable displacement hydraulic pump is controlled according to the operation amount of the pilot valve, that is, in proportion to the pilot pressure. The predetermined speed control mode is a mode in which the discharge capacity of the hydraulic pump is controlled by the fixed secondary pressure generated by the pressure reducing valve.

Therefore, in this independent speed control mode, the hydraulic motor
It is possible to control the speed of each of the 8 and 80 individually or to control the predetermined speed individually. For example, when used for the above-mentioned underground wall bucket work, the secondary pressure generated by the pressure reducing valves 5 and 50 is set according to the hydraulic efficiency of the main winding winch and the auxiliary winding winch, and the first and second The electromagnetic switching valves 6 and 60 are excited to switch to the B position for use. Since the discharge capacity of each hydraulic pump 7, 70 differs by the difference in hydraulic efficiency and the discharge flow rate differs, the pilot valve 1, 10 can be operated by full stroke, for example, and fixed in the detent position to improve hydraulic efficiency. Even if they are different, the hydraulic motors 8 and 80 can be driven at a constant speed,
The speed of the main winding and auxiliary winding can be controlled at a constant speed.

<2> Equal Volume Control Mode This is a mode in which the discharge volumes of the hydraulic pumps 7, 70 are controlled to be equal volumes, and the electromagnetic switching valve 22 is selected by switching to the low position.

In this case, the first and second regulators 7a and 70a are communicated with each other, and when the switching valve 6 is set to the a position, each pilot valve
The higher pilot pressure from 1, 10 is applied to each regulator 7a, 70a, and the discharge capacities of both variable displacement hydraulic pumps 7, 70 become equal. When the switching valve 6 is set to the low position, either one of the secondary pressures from the pressure reducing valves 5 and 50 is applied.

Therefore, for example, when the hydraulic motors 8 and 80 are left and right traveling motors, the first and second electromagnetic switching valves 6 and 60 are switched to the a position, and the variable speed control mode is set to set the pilot valve.
Operate 1,10 by the same amount. Thereby, the first and second
Since the same pilot pressure acts on the regulators 7a, 70a of the above, the discharge capacities of the first and second variable displacement hydraulic pumps 7, 70 become equal, and both hydraulic motors 8, 80 rotate at a constant speed and go straight. It becomes possible to drive. The same applies when the pilot valves 1 and 10 are fully stroked and locked in the detent position.

FIG. 2 shows a more specific circuit configuration of the hydraulic crane. The same parts as those in FIG. 1 will be described with the same reference numerals.

The first variable displacement hydraulic pump 7 includes a traveling right hydraulic motor.
8A and main winding hydraulic motor 8B are connected in series via control valves 4A and 4B. The second variable displacement hydraulic pump 70 includes a traveling left hydraulic motor 80A and a boom hoisting hydraulic motor 8A.
0B and auxiliary winding hydraulic motor 80C are connected in series via control valves 40A to 40C. Control valves 4A, 4B and 40A-40
C is switched and controlled by pilot valves 1A, 1B, 10A to 10C, respectively. Further, the pilot pressure from each pilot valve 1, 10 and the secondary pressure of the pressure reducing valve 5, 50 are connected to the regulators 7a, 70a of the corresponding hydraulic pumps 7, 70, respectively, by the electromagnetic switching valve 6,
It is configured to be applied via 60.

Even in such a hydraulic circuit, the independent capacity control mode and the equal capacity control mode can be selectively selected by appropriately switching the electromagnetic switching valves 6, 60, 22 as described above, and the selected capacity control mode can be selected. Among them, the variable speed control mode and the predetermined speed control mode can be further selected.

In the configuration of the above embodiment, the first and second hydraulic motors 8 and 80 operate the first and second actuators as control valves.
4,40 are first and second valve means, pilot valves 1,10 are first and second operating means, pressure reducing valves 5,50 are first and second signal generating means, and electromagnetic switching is performed. The valves 6 and 60 constitute speed mode switching means, and the electromagnetic switching valve 22 constitutes capacity mode switching means.

Although the present invention has been described above with respect to the hydraulic crane, the present invention can be applied to other construction machines, work machines, and work vehicles. Further, although the actuator has been described as a hydraulic motor, it can also be used as a speed control circuit for a hydraulic cylinder or the like. Furthermore, although the control valves and regulators are operated by pilot hydraulic pressure, each of them is a control valve or regulator controlled by an electric signal, and a potentiometer that outputs an electric signal proportional to the operation amount is used as an operation member. May be used.

G. Effect of the Invention According to the present invention, the discharge capacities of a plurality of variable displacement hydraulic pumps that supply pressure oil to a plurality of actuators are controlled to different values independently of each other and can be controlled to the same value in conjunction with each other. In addition, since the discharge capacity of each variable displacement hydraulic pump is controlled to an arbitrary value according to the manipulated variable and also to a predetermined value, it is possible to control a plurality of actuators at a predetermined constant speed. As well as being able to control at different speeds. Therefore, for example, in the work of repeatedly operating the discharge capacity to different constant values in order to rotate the main winding hydraulic motor and the auxiliary winding hydraulic motor at the same speed for a certain period of time, each operating member is delicately operated. Both hydraulic motors can be controlled at a constant speed without operation. Of course, the two actuators can also be driven at different speeds. Further, for example, the straightness can be easily selected by tuning the left and right hydraulic motors as in a traveling operation.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing an embodiment of the present invention, FIG. 2 is a hydraulic circuit diagram showing a concrete example when applied to a hydraulic crane, and FIGS. 3 and 4 are hydraulic circuit showing a conventional example. It is a figure. 1,10: Pilot valve, 4,40: Control valve 5,50: Pressure reducing valve, 6,60: Electromagnetic switching valve 7,70: Hydraulic pump, 7a, 70a: Regulator 8,80: Hydraulic motor, 22: Electromagnetic Type switching valve

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location F15B 11/00 11/04 11/22 C 9026-3H 8512-3H F15B 11/04 B

Claims (1)

[Claims] Claims: 1. First and second variable displacement hydraulic pumps having regulators for variably controlling discharge capacity and supplying pressure oil to first and second actuators, respectively, and first and second variable displacement hydraulic pumps. First and second valve means for adjusting the flow of the discharge oil of the pump to control the driving of the first and second actuators, respectively, and valve control for individually controlling the first and second valve means, respectively. A signal and a variable regulator control signal for variably controlling the regulator individually
And a second operating means, the speed control circuit is applied to the regulator separately from the variable regulator control signal for setting the discharge capacities of the first and second variable displacement hydraulic pumps to a predetermined value. First and second signal output means for outputting a regulator control signal for a predetermined speed, a variable speed control mode for applying the variable regulator control signal to the regulator, and a predetermined for applying the regulator control signal for the predetermined speed to the regulator One of the first and second regulator control signals, one of the regulator control signal, and a speed mode switching selection unit that switches between speed control modes, an independent capacity control mode that independently applies the regulator control signal to each regulator. Capacitance mode that switches between equal-capacity control mode that is commonly applied to regulators Speed control circuit having a variable displacement hydraulic pump which is characterized by comprising a switching means.